Page 12, O2 Uptake, Exercise & Cor. Circ., Dr. D. Penney

Effects of Endurance Training

Aerobic endurance exercise training produces both central (i.e. heart) and peripheral (i.e. skeletal muscle and vascular bed) adaptations (Table 3.01). Centrally, increased cardiac output and stroke volume are seen at maximal exercise levels, but maximal heart rate is unchanged. There are also increases in central blood volume and total hemoglobin.

Peripherally, skeletal muscle mitochondria increase in size and number, and the content of oxidative enzymes is augmented. In addition, muscle fiber myoglobin concentration increases and the density of capillaries surrounding the cells rise. These peripheral changes increase the ability of the tissue to use O2, and are responsible for elevating A-V O2 diff. Trained individuals also have greater muscle glycogen and are able to tolerate higher blood lactate levels. Click here for a summary of training effects.